Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

Is it possible to create a symbolic link to the output of a command?

Posted on 2011-09-26
8
Medium Priority
?
380 Views
Last Modified: 2012-05-12
I'd like to try to do something like this:

ln -s "tac ~/myfile.txt" linkname

the above of course doesn't work but is there some way to achieve this effect?

Essentially I want a symbolic link to a file with the contents in the reverse order.
0
Comment
Question by:opike
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
8 Comments
 
LVL 4

Accepted Solution

by:
sakman earned 504 total points
ID: 36601397
If I understand you correctly, then nope.  A symbolic link just points to an existing file an only contains the information needed to find that file.
0
 
LVL 48

Assisted Solution

by:Tintin
Tintin earned 500 total points
ID: 36601688
Not possible.

A symbolic link can't reference a file that has different content.

0
 
LVL 38

Assisted Solution

by:wesly_chen
wesly_chen earned 500 total points
ID: 36602451
> ln -s "tac ~/myfile.txt" linkname
tac  ~/myfile.txt  >  linkname

If the content of ~/myfile.txt is changed constantly, then set up a cron job to run it frequently.

crontab -e
* * * * *  /usr/bin/tac  /home/<login name>/myfile  > /hone/<login name>/linkname
0
VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

 

Author Comment

by:opike
ID: 36634550
@wesley - That was my plan b.  I was hoping there was some way to point directly to the reverse of the file rather then set up some intermediate, periodic copy-type operation, but apparently there isn't.
0
 
LVL 38

Expert Comment

by:wesly_chen
ID: 36650960
symbolic link is a pointer to a EXISTING file or directory.
The file with different content will be the different file. So you need to have that file exist before you can create symbolic point to it.
0
 
LVL 12

Assisted Solution

by:hfraser
hfraser earned 248 total points
ID: 36699191
Depending upon how sophisticated you want to go or how important it is to accomplish something like this, you could look at FUSE (Filesystem in Userspace) at

http://fuse.sourceforge.net/

This allows you to have a file that effectively maps to some code you've created, which in your case could be a view of a file in reverse order.
0
 
LVL 84

Assisted Solution

by:ozo
ozo earned 248 total points
ID: 36707782
Are you asking for something like
ln -s `tac ~/myfile.txt` linkname
or are you trying to do something more like
cat >linkname <<END
#!/bin/sh
tac ~/myfile.txt
END
chmod a+x linkname
0
 

Author Comment

by:opike
ID: 36714122
I my ultimate goal was to access a file from a url through webserver (and I wanted a direct link, not something that would be periodically copied).

I knew this could be done through php (which is what I ended up doing) but I wanted to see if it could be done through a shell script (more out of curiosity I suppose).
0

Featured Post

[Webinar] Lessons on Recovering from Petya

Skyport is working hard to help customers recover from recent attacks, like the Petya worm. This work has brought to light some important lessons. New malware attacks like this can take down your entire environment. Learn from others mistakes on how to prevent Petya like worms.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I. Introduction There's an interesting discussion going on now in an Experts Exchange Group — Attachments with no extension (http://www.experts-exchange.com/discussions/210281/Attachments-with-no-extension.html). This reminded me of questions tha…
Google Drive is extremely cheap offsite storage, and it's even possible to get extra storage for free for two years.  You can use the free account 15GB, and if you have an Android device..when you install Google Drive for the first time it will give…
Learn how to get help with Linux/Unix bash shell commands. Use help to read help documents for built in bash shell commands.: Use man to interface with the online reference manuals for shell commands.: Use man to search man pages for unknown command…
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
Suggested Courses

618 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question